About 17,000 spare parts used for the U.S. fifth-generation stealth fighter F-35 have been found missing from the official inventory management system. The parts are worth at least $1.3 billion, raising criticism that weak inventory controls at the U.S. Defense Department could harm fighter operations and fiscal soundness.

On Nov. 10, John Militair said the U.S. Government Accountability Office (GAO) said in an audit report released the previous day that the F-35 Joint Program Office (JPO) parts tracking and management system remains inaccurate and incomplete.

The GAO said about 26 million F-35 parts are stored across some 700 facilities worldwide, with a total value of $31 billion.

But as of March this year, about 17,000 parts undergoing maintenance or repair were not registered in the JPO’s Enterprise Logistics Management System (ELMS). The book value of the omitted parts is about $1.3 billion, and it could reach as much as $2.5 billion after including shipping and other acquisition costs.

The problem is that the manufacturer’s and the Defense Department’s management systems are not linked. ELMS can update inventories in real time, but it is not directly connected to the management systems of Lockheed Martin and Pratt & Whitney.

As a result, the JPO is separately inputting information received from multiple sources. In particular, data on shared spare-parts inventories are provided quarterly, meaning they can lag actual conditions by more than three months.

Controls over lost parts were also lax. The GAO said a 2023 audit flagged losses of more than 1 million parts from 2018 to 2022 worth about $85 million. But the JPO still failed in this audit to properly grasp the status of how those losses were handled.

Concerns over the reliability of inventory information could also affect fighter operations. If exact locations and quantities cannot be confirmed, it becomes harder to secure needed parts on time or forecast maintenance demand.

The GAO recommended four improvements, including procedures to track losses and training for staff, and the Defense Department accepted all of them. The department aims to complete its first full inventory inspection by March the following year.

The roughly 17,000 items identified this time were parts not registered in the management system, and actual loss or theft has not been confirmed.